Immunoglobulin preparation and storage system for an immunoglobulin preparation

ABSTRACT

The present invention relates to an immunoglobulin preparation comprising immunoglobulin in a mass-volume percentage of at least 4%, wherein the concentration of oxygen dissolved in the preparation at room temperature is less than 40 μmol/l.

This application is the United States national stage of PCT/EP2011/052770, filed Feb. 24, 2011, (published as WO 2011/104315), and also claims priority to European Patent Application No. 10 001 996.7, filed Feb. 26, 2010, and U.S. Provisional Application No. 61/282,548, filed Feb. 26, 2010, all of which are incorporated herein by reference.

The present invention relates to an immunoglobulin (Ig) preparation with improved stability for storage.

The invention further relates to a storage system for the Ig preparation, to a process for providing such a storage system and to the use of a gas having an oxygen content of less than 20 vol-% for increasing the storage stability of an Ig preparation.

Ig preparations for Ig replacement therapy, e.g. for the treatment of primary immunodeficiency (PID) disorders, such as common variable immunodeficiency (CVID) and X-linked agammaglobulinemia, are widely known in the art. Such Ig preparations are commonly obtained from human plasma and are stored in vials for further use. The preparation can then be administered intravenously (IVIg) or subcutaneously (SCIg) to the patient in need of the therapy.

When using the subcutaneous route, Ig preparations having a relatively high Ig concentration are desirable, since they allow for a less frequent administration and/or an administration of smaller volumes than a preparation of lower concentration.

If stored over several months, known Ig preparations tend to become yellowish in colour. This effect is particularly pronounced for Ig preparations having a relatively high Ig concentration and exposed to stress conditions like light exposure and/or elevated temperature; said preparations typically show a relatively strong, yellow-brownish coloration already after storage of two months.

Such a coloration is however in conflict to standard requirements for Ig preparations. The European Pharmacopoeia, for example, requires the preparation to remain clear-yellow or light brown.

One possible approach to cope with this problem is to store the Ig preparation in a dark environment. A further approach is to store the Ig preparation at a relatively low temperature, for example at about 5° C. Although both approaches have shown to result in a reduction of yellowish coloration, they are inconvenient for the handling and are relatively burdensome to put into practice, since the respective environment has to be maintained over the whole storage period.

It is therefore an object of the present invention to provide an Ig preparation for Ig replacement therapy, which shows a reduced yellowish coloration and thus allows for complying with the standard requirements concerning coloration even after prolonged storage under light and under room temperature. It is a further object to provide a storage system for storing the preparation in a manner such that the yellowish coloration is reduced, thus allowing for complying with the standard requirements concerning coloration even after prolonged storage under stress conditions like exposure to light and/or elevated temperature.

The problem is solved by the Ig preparation and the storage system according to the independent claims. Preferred embodiments are subject of the dependent claims.

According to a first aspect, the present invention thus relates to an Ig preparation comprising Ig in a mass-volume percentage of at least 4% (i.e. 4 g/100 ml). In contrast to naturally occurring biological fluids, the liquid Ig preparation of the present invention is thus enriched in Ig. Given its relatively high Ig concentration, the preparation is suitable for Ig replacement therapy. Preparations of 10% or more are suitable for subcutaneous administration which may be performed by the patients themselves.

It has surprisingly been found that if the concentration of oxygen dissolved in the preparation at room temperature is less than 200 μmol/l, a high stability against yellowish coloration over a prolonged period of time can be achieved. Preferably, the yellowish coloration is caused by stress factors other than light exposure, i.e. occurs in the dark, is not caused by photodegradation. In particular, a stable Ig preparation showing only a slight yellowish coloration or no yellowish coloration at all can be achieved, thus meeting standard requirements, e.g. of the European Pharmacopoeia, even after a prolonged storage period of 24 months, even of 36 months, or longer. In particular, a stable Ig preparation meeting the standard requirements can be achieved, even after a prolonged storage period of 24 months, even of 36 months, at room temperature in the dark. The absorbance A_(350-500 nm) of the stable immunoglobulin preparation remains below 0.28 upon storage for 24 months at 25° C. in the dark, preferably the stable immunoglobulin preparation has a concentration of 20% w/v. In a preferred embodiment of the invention, the absorbance A_(350-500 nm) remains below 0.355 when measured for a 20% Ig preparation after storage for 6 months at 37° C. in the dark. The stable immunoglobulin preparation shows an increase in A_(350-500 nm) of less than 0.18, preferably of less than 0.17, even more preferably of less than 0.16, when stored at 25° C. in the dark for 36 months. The stable immunoglobulin preparation shows an increase in A_(350-500 nm) of less than 0.22, preferably of less than 0.20, even more preferably of less than 0.19, when stored at 37° C. in the dark for 6 months.

Methods for determining the concentration of oxygen dissolved in the Ig preparation are well known to the skilled person. For example, the oxygen concentration can be determined by a polarographic method, using e.g. a Clark electrode. Alternatively, also luminescence oxygen sensing can for example be used for determining the oxygen concentration in the preparation.

When contained in a container, the Ig preparation's oxygen concentration can be determined using an electrode extending into the container and into the Ig preparation contained therein. Alternatively, the Ig preparation's oxygen concentration can be determined after opening of the container. In this latter case, determination is carried out within 5 minutes after opening of the container in order to avoid corruption of the respective result by an increase of the oxygen content of the gas which is in contact with the immunoglobulin preparation.

Without wanting to be bound by the theory, it is assumed that the yellowish coloration typically seen with conventional Ig preparations is due to an oxidative alteration of the Ig contained therein. According to the present invention, this oxidative alteration is reduced by maintaining the amount of oxygen dissolved in the preparation at a concentration lower than the concentration that would be established if the preparation is stored under air at atmospheric pressure.

Given the fact that according to the present invention an Ig preparation can be obtained, which even after prolonged storage shows only a slight yellowish coloration or no yellowish coloration at all, both patients and physicians can readily acknowledge that the Ig contained therein is in good quality, which further contributes to an increase in the acceptance of the preparation.

Apart from being indicative for a low degree of presumably oxidative Ig alteration, a colourless or only slightly coloured preparation is visually much more appealing than a yellow or a yellow-brownish one.

A particularly high stability of the Ig preparation of the present invention can be achieved if the concentration of oxygen dissolved at room temperature is less than 175 μmol/l, preferably less than 150 μmol/l, more preferably less than 125 μmol/l, and most preferably less than 100 μmol/l.

Since for conventional Ig preparations, the effect of yellowish coloration is particularly pronounced for preparations having a high Ig concentration, the present invention particularly refers to a preparation comprising Ig in a mass-volume percentage of at least 5%, preferably at least 10%, more preferably at least 12%, more preferably at least 14%, more preferably at least 16%, more preferably at least 18%, and most preferably at least 20%. Preferably, the Ig preparation is a polyclonal Ig preparation, more preferably a polyclonal IgG preparation.

Compliance of the Ig preparation with the respective coloration requirements of the European Pharmacopoeia can be determined by the respective method given therein (Ph. Eur. 5.5, 2006, General methods 2.2.2 Degree of Coloration of Liquids).

Alternatively, compliance with the coloration requirements can also be determined by a spectrophotometric method, the results of which have been found to correlate with the results of the method according to the European Pharmacopoeia. Specifically, it has been found that an Ig preparation having a mean optical density A_(350-500 nm) (i.e. absorbance at 350 nm minus absorbance at the reference wavelength 500 nm) of less than 0.355 fully complies with the respective requirements of the European Pharmacopoeia.

When stored over 24 months at 25° C. in the dark, a mean increase of the optical density (absorbance) A_(350-500 nm) of only about 0.1 can be achieved according to the present invention, when stored over 36 months at 25° C. in the dark, a mean increase of the optical density of only about 0.15 can be achieved (corresponding to an approximate monthly increase of the absorbance of 0.004). When stored over 3 months at 5° C. under light exposure, a mean increase of the optical density A_(350-500 nm) of only about 0.04 can be achieved according to the present invention (corresponding to an approximate monthly increase of the absorbance of 0.01), which is in clear contrast to the mean increase for an Ig preparation in which the oxygen concentration is not reduced according to the present invention, said increase being about 1.2 (corresponding to an approximate monthly increase of the absorbance of 0.40). Further, when stored over 6 months at 37° C. in the dark, a mean increase of the optical density A_(350-500 nm) of only about 0.18 can be achieved according to the present invention (corresponding to an approximate monthly increase of the absorbance of 0.03), which is in clear contrast to the mean increase for an Ig preparation in which the oxygen concentration is not reduced according to the present invention, said increase being about 0.24 (corresponding to an approximate monthly increase of the absorbance of 0.04).

The Ig preparations of the present invention can be used both for the intravenous and the subcutaneous administration to a patient, by way of a non-limiting example for the treatment of PID or CVID. The use for the subcutaneous administration is however preferred.

Given the high concentration of Ig, the present invention allows smaller volumes of the preparation to be administered to the patient while maintaining the efficacy compared to conventionally available preparations having a lower Ig concentration.

Since the Ig preparation according to the present invention is preferably used for the subcutaneous administration to a human, the present invention also relates to the use of the Ig preparation for the preparation of a medicament for subcutaneous administration to a human. As for example reported by S. Misbah et al, Clinical and Experimental Immunology, 158 (Suppl. 1); pp. 51-59, there are various advantages of the subcutaneous administration of the preparation over the intravenous administration. In particular, venous access is not required and the need for premedication with corticosteroids and anti-histamines is reduced.

Also, when using the subcutaneous administration route the marked peaks typically seen with monthly IVIg infusions are dampened and persistently elevated Ig levels are obtained leading to a reduction in systemic side effects.

Preferably, the Ig comprised in the Ig preparation of the present invention essentially consists of IgG, but is in no way limited thereto. According to other preferred embodiments of the preparation of the present invention, the Ig comprises or essentially consists of IgM or comprises or essentially consists of IgA, respectively.

According to another aspect, the present invention further relates to a storage system for an Ig preparation, preferably a polyclonal Ig preparation, said storage system comprising a container having an interior, a first portion of said interior being occupied by the Ig preparation and the remaining second portion of said interior forming a headspace and being occupied by a gas, wherein in the gas of the headspace the content of oxygen is less than 20 vol-%. In the context of the present invention, the term “vol-%” has the meaning commonly used in the technical field and denotes the volume ratio of the respective gas component in relation to the total volume of the gas in which it is contained.

The gas in the headspace of the storage system of the present invention thus has a reduced oxygen content compared to the surrounding air. If stored in such a storage system, the oxygen dissolved in the Ig preparation can thus be kept at a concentration below 200 μmol/l, preferably below 175 μmol/l, more preferably below 150 μmol/l, even more preferably below 125 μmol/l, and most preferably below 100 μmol/l over a prolonged storage period, and yellowish coloration can be vastly reduced even if the Ig preparation is stored under light and at room temperature.

Methods for determining the oxygen content in the gas of the headspace are known to a skilled person. For example, the oxygen content can be determined by laser absorption spectroscopy, in particular tuneable diode laser absorption spectroscopy, thus eliminating interference of other components contained in the headspace gas. Specifically, the oxygen content can be determined by means of a device of the type LaserGas™ II (LaserGas Oy, Finland), whereby the absorption line of oxygen is scanned by means of a single-mode diode. The absorption of light by the oxygen molecules is measured by a detector, based on which the oxygen content of the headspace gas can be calculated.

It is preferred that in the gas of the headspace the content of oxygen is less than 16 vol-%, preferably less than 12 vol-%, more preferably less than 10 vol-%, and most preferably less than 7 vol-%. An oxygen content of less than 7 vol-% has been found to be particularly preferred, since Ig preparations stored under a respective headspace in the container has been shown to fully comply with the requirements of the European Pharmacopoeia even after a prolonged storage period of 24 months or longer, even after a storage period of 36 months or longer, even when stored at 25° C. (in the dark), as will be shown in detail below.

According to a very straightforward and thus preferred embodiment, the gas of the headspace is at least approximately at atmospheric pressure.

It is further preferred that in the gas of the headspace the content of inert gas is more than 80 vol-%, preferably more than 84 vol-%, more preferably more than 88 vol-%, more preferably more than 90 vol-%, and most preferably more than 93 vol-%. The inert gas may be e.g. nitrogen, argon, other noble gases or mixtures thereof. Given its availability, nitrogen is preferably used.

It is further preferred that the container of the gas-tight storage system comprises a vial, in particular a vial as standardized by DIN/ISO 8362-1.

According to a further preferred embodiment, the volume ratio of the headspace to the Ig preparation ranges from about 0.1:1 to 0.9:1, depending on the vial used. For a 6R vial, for example, the ratio is typically about 0.9:1 whereas for a 20R vial, the ratio is typically at about 0.1:1.

In particular, the storage system of the invention improves the stability of an Ig preparation after a prolonged storage period of 24 months, even of 36 months, at room temperature in the dark. When using a 20% Ig preparation as reference, the storage system of the invention provides that the absorbance A_(350-500 nm) of the immunoglobulin preparation remains below 0.28 upon storage for 24 months at 25° C. in the dark, preferably the absorbance A_(350-500 nm) remains below 0.355 when measured for a 20% Ig preparation after storage for 6 months at 37° C. in the dark. The storage system of the invention provides a stable immunoglobulin preparation showing an increase in A_(350-500 nm) of less than 0.18, preferably of less than 0.17, even more preferably of less than 0.16, when stored at 25° C. in the dark for 36 months. The storage system of the invention provides a stable immunoglobulin preparation showing an increase in A_(350-500 nm) of less than 0.22, preferably of less than 0.20, even more preferably of less than 0.19, when stored at 37° C. in the dark for 6 months.

According to a further aspect, the present invention also relates to a process for providing a storage system for an Ig preparation comprising the steps that the Ig preparation is filled into a container and the container is sealed, wherein prior to the sealing the headspace of the container is filled with a gas such that the oxygen content in the gas of the headspace is less than 20 vol-%, preferably less than 16 vol-%, more preferably less than 12 vol-%, even more preferably less than 10 vol-%, and most preferably less than 7 vol-%. This “inert gassing” of the headspace allows the concentration of the oxygen dissolved to be kept at a concentration below 200 μmol/l preferably below 175 μmol/l, more preferably below 150 μmol/l, even more preferably below 125 μmol/l, and most preferably below 100 μmol/l over a prolonged storage period. Preferably, the prolonged storage period is longer than 24 months, preferably even longer than 36 months, at 25° C. (or room temperature) in the dark. In particular, the process of the invention improves the stability of an Ig preparation after a prolonged storage period of 24 months, even of 36 months, at room temperature in the dark. When using a 20% Ig preparation as reference, the process of the invention provides that the absorbance A_(350-500 nm) of the immunoglobulin preparation remains below 0.28 upon storage for 24 months at 25° C. in the dark, preferably the absorbance A_(350-500 nm) remains below 0.355 when measured for a 20% Ig preparation after storage for 6 months at 37° C. in the dark. The process of the invention provides a stable immunoglobulin preparation showing an increase in A_(350-500 nm) of less than 0.18, preferably of less than 0.17, even more preferably of less than 0.16, when stored at 25° C. in the dark for 36 months. The process of the invention provides a stable immunoglobulin preparation showing an increase in A_(350-500 nm) of less than 0.22, preferably of less than 0.20, even more preferably of less than 0.19, when stored at 37° C. in the dark for 6 months.

Preferably, the gas of the headspace of the storage system obtained is at atmospheric pressure.

Alternatively or additionally to the above process, an Ig preparation defined above with a reduced concentration of oxygen dissolved can be obtained by subjecting the Ig preparation or its solvent to a degassing step and/or a gassing step using an inert gas. It is thereby preferred that the solvent of the Ig preparation, typically water, is subjected to the degassing and/or gassing step prior to the formulation of the Ig preparation. Degassing can for example be obtained by storing the solvent at an elevated temperature or at a reduced pressure. Gassing using an inert gas can for example be performed by introducing the inert gas into the respective preparation or its solvent.

In accordance with the above, the present invention relates according to a further aspect also to the use of a gas having an oxygen content of less than 20 vol-% for increasing the storage stability of an immunoglobulin preparation comprising immunoglobulin in a mass-volume percentage of at least 4%. As given above, the gas is thereby preferably used in the headspace of a container in which the Ig preparation is stored.

With the storage system of the invention, or the process of the invention, or the use of a gas with an oxygen content of less than 20% according to the invention, a reduction in the mean increase of absorbance at 350nm for an Ig preparation of at least 10% is achievable, preferably of more than 12%, 14%, 16%, 18% or 20%, more preferably of more than 25%, 30%, 35%, 38%, 40%, or even 45% can be achieved when stored for a prolonged period in the dark. With the storage system or process of the invention, this can be achieved for preparations comprising Ig in a mass-volume percentage of at least 5%, preferably at least 10%, more preferably at least 12%, more preferably at least 14%, more preferably at least 16%, more preferably at least 18%, and most preferably at least 20%.

A detailed description of a process according to the present invention is given in the example below.

EXAMPLES

Ig preparation

The technical effect achieved by the present invention was assessed using IgPro20.

IgPro20 is a ready-to-use, 20% (200 g/l) liquid preparation of polyvalent human IgG for subcutaneous administration, manufactured from large pools of human plasma. Its protein moiety is ≧98% IgG, of which over 90% is in the form of monomers+dimers. IgPro20 is formulated with the stabilizer L-proline (250 mmol/L) at pH 4.8 without preservatives.

Filling of the Ig Preparation

During aseptic filling of IgPro20 into a vial, the headspace of the vial was gassed with nitrogen.

Specifically, gassing with nitrogen was carried out in two steps:

-   a) directly after introducing the Ig preparation into the vial,     sterile-filtered nitrogen gas was filled into the headspace by means     of an inflation needle extending into the headspace; -   b) during insertion of the plug for sealing the vial, nitrogen gas     was blown onto the opening of the vial by a further inflation needle     extending in angular direction with regard to the axis of the     opening.

The nitrogen gas used was sterile-filtered using a sterile filter of the type KA02PFRP8 of Pall Corporation. The operating pressure of the gassing equipment was set to about 0.5 bar.

By the above procedure, a storage system can be provided having a headspace which immediately after sealing of the vial has an oxygen content of less than 4.5 vol-%. Given the fact that the preparation is not degassed or gassed with an inert gas before filling into the vial, the oxygen content in the gas of the headspace might increase until an equilibrium between the immunoglobulin and the gas is established. Even in this case, the content of oxygen remains below 7 vol-%.

Storage Conditions

The storage conditions and test intervals of the long-term stability program for IgPro20 were chosen according to the International Conference on Harmonization (ICH) of Technical Requirements for Registration of Pharmaceuticals for Human Use guideline Q1A(R2). Long-term storage for up to 24 months at 25° C. is shown in FIG. 3 below.

In order to simulate secondary packaging, the vials were stored at a temperature of 37° C. in the dark.

A horizontal position of the container maintained contact of the solution with the stopper, in accordance with ICH guideline Q5C.

Quantification of Yellowish Coloration

In order to quantify yellowing of the Ig preparation, its mean optical density at 350 to 500 nm has been determined after several intervals of storing. This is based on the finding that the mean optical density can be correlated to the standardized examination of the coloration of liquids as described in the European Pharmacopoeia (Ph. Eur. 5.6, January 2005, General methods 2.2.2, Degree of Coloration of Liquids).

The technical effect achieved by the present invention is illustrated by way of the attached figures, of which

FIG. 1 is a graphical representation of the optical density (absorbance) A_(350-500 nm) of the Ig preparation stored as a function of storage time after storage at 5° C. under light without inert gassing of the headspace (diamonds), using a gas in the headspace having an oxygen content of 16 vol-% (squares), 12 vol-% (triangles), 10 vol-% (crosses), 7 vol-% (stars) and less than 7 vol-% (circles), respectively; and

FIG. 2 is a graphical representation of the optical density (absorbance) A_(350-500 nm) of the Ig preparation stored as a function of storage time after storage at 37° C. in the dark without inert gassing of the headspace (diamonds) and using a gas in the headspace having an oxygen content of at most 7 vol-% (squares), respectively, and

FIG. 3 is a graphical representation of the mean optical density (absorbance) A_(350-500 nm) of a number of samples of the Ig preparation as a function of storage time when stored at 25° C. in the dark using a gas in the headspace having an oxygen content of less than 7 vol-%.

As can be seen from FIG. 1, yellowing of the immunoglobulin preparation overtime is reduced by using a gas having a reduced oxygen content (and thus also a reduced oxygen partial pressure) in the headspace. Specifically, by using a gas having an oxygen content of less than 7 vol-%, the optical density A_(350-500 nm) is less than 0.35 even after storage for 6 months, thus fully complying with the requirements of the European Pharmacopoeia after prolonged storage. The concentration of oxygen dissolved in the respective sample at room temperature is less than 100 μmol/l.

Referring to FIG. 2, a mean increase of the optical density A_(350-500 nm) of only about 0.18 can be achieved according to the present invention when stored over 6 months at 37° C. in the dark using a gas in the headspace having an oxygen content of at most 7 vol-%. This is in clear contrast to the mean increase for an Ig preparation stored without gassing of the headspace, said increase being about 0.24.

As shown in FIG. 3, a mean increase of the mean optical density A_(350-500 nm) of only about 0.1 can be achieved according to the present invention when stored over 24 months at 25° C. in the dark.

As shown in Table 1 below, the mean optical density is still below 0.355 even after storage over 36 months at 25° C. in the dark, and even lower if stored at 5° C. in the dark. The values of 6 different lots are shown.

TABLE 1 25° C. 5° C. 30 months 36 months 30 months 36 months O₂ O₂ O₂ O₂ μmol/L % O₂ A₃₅₀ μmol/L % O₂ A₃₅₀ μmol/L % O₂ A₃₅₀ μmol/L % O₂ A₃₅₀ 79.2 6.3 0.270 83.5 6.6 0.319 61.3 4.8 0.156 58.4 4.6 0.158 75.8 6.0 0.229 79.9 6.3 0.249 56.0 4.4 0.132 54.8 4.3 0.130 82.4 6.5 0.297 86.3 6.8 0.332 65.3 5.1 0.181 62.4 4.9 0.186 53.3 4.2 0.298 54.3 4.3 0.289 66.0 5.2 0.155 62.3 4.9 0.159 55.7 4.4 0.231 57.3 4.5 0.244 62.3 4.9 0.133 58.5 4.6 0.131 54.7 4.3 0.290 56.3 4.4 0.318 63.5 5.0 0.180 59.8 4.7 0.179

Table 2 shows the mean monthly increase in absorbance A_(350-500 nm) in different storage conditions. For all conditions tested, keeping the oxygen concentration below 100 μmol/l, or below 7% oxygen in the headspace, leads to significantly lower increase in absorbance, indicating significantly higher stability of the IgG preparation. All samples were stored in the dark. Data were collected for 24 or 36 months: during this time, the increase of absorbance over time was about linear.

TABLE 2 Mean monthly A_(350-500 nm) Storage Oxygen in increase in reduction temperature headspace A_(350-500 nm) by O2 reduction 37° C. <7% 0.030 42.5% 20% (air) 0.052 25° C. <7% 0.0042 19.9% 20% (air) 0.0052  5° C. <7% 0.00037 47.8% 20% (air) 0.00071 

The invention claimed is:
 1. A ready-to-use liquid immunoglobulin preparation for intravenous or subcutaneous administration comprising immunoglobulin in a mass-volume percentage of at least 4%, wherein the concentration of oxygen dissolved in the preparation at room temperature is less than 200 μmol/l, wherein the absorbance at 350 nm minus the absorbance at 500 nm (absorbance A_(350-500 nm)) of the immunoglobulin preparation remains below 0.28 upon storage for 24 months at 25° C. in the dark, and wherein the preparation is comprised within a container with a headspace occupied by a gas other than air, wherein the content of oxygen in the gas of the headspace remains less than 20 vol-% during said storage.
 2. The immunoglobulin preparation according to claim 1, wherein the concentration of oxygen dissolved in the preparation at room temperature is less than 175 μmol/l.
 3. The immunoglobulin preparation according to claim 1, wherein the immunoglobulin preparation comprises immunoglobulin in a mass-volume percentage of at least 5%.
 4. The immunoglobulin preparation according to claim 1, wherein the immunoglobulin comprised in the immunoglobulin preparation consists essentially of IgG.
 5. The immunoglobulin preparation according to claim 1, wherein the preparation has a mean increase in absorbance A_(350-500 nm) of less than 0.2 upon storage of 6 months at 37° C. in the dark.
 6. Storage system for a ready-to-use liquid immunoglobulin preparation for intravenous or subcutaneous administration comprising a container having an interior, a first portion of said interior being occupied by the ready-to-use liquid immunoglobulin preparation comprising immunoglobulin in a mass-volume percentage of at least 4%, and the remaining portion of said interior forming a headspace and being occupied by a gas other than air, wherein the content of oxygen in the gas of the headspace is less than 20 vol-%, and wherein the absorbance A_(350-500 nm) of the immunoglobulin preparation in the container remains below 0.28 upon storage for 24 months at 25° C. in the dark.
 7. The storage system according to claim 6, wherein the content of oxygen in the gas of the headspace is less than 16 vol-%.
 8. The storage system according to claim 6, wherein the gas of the headspace is at approximately atmospheric or higher than atmospheric pressure.
 9. The storage system according to claim 6, wherein the content of inert gas in the gas of the headspace is more than 80 vol-%.
 10. The storage system according to claim 6, wherein the container is a vial.
 11. The storage system according to claim 6, wherein the headspace and the immunoglobulin preparation are in a volume ratio that ranges from 0.1:1 to 0.9:1.
 12. The storage system according to claim 6, wherein the storage system has a mean monthly increase of absorbance A_(350-500 nm) that is at least 10% lower than the mean monthly increase of absorbance A_(350-500 nm) observed when air is used as the gas in the headspace.
 13. Process for preparing a storage system for an immunoglobulin preparation, comprising filing a container with the immunoglobulin preparation according to claim 1, filling the container with a gas other than air, and sealing the container, wherein the gas forms a headspace above the preparation, and wherein the gas of the headspace has an oxygen content of less than 20 vol-%.
 14. The process according to claim 13, wherein the gas filled into the container is at atmospheric pressure.
 15. The process according to claim 13, wherein the immunoglobulin preparation comprises immunoglobulin in a solvent, and wherein the process comprises subjecting the immunoglobulin and/or its solvent to a degassing step and/or a gassing step using an inert gas.
 16. The process according to claim 15, wherein the solvent is subjected to the degassing and/or gassing step using an inert gas prior to formulation of the preparation.
 17. The immunoglobulin preparation according to claim 1, wherein the immunoglobulin preparation comprises immunoglobulin in a mass-volume percentage of 14-20%.
 18. The immunoglobulin preparation according to claim 1, wherein the immunoglobulin preparation comprises immunoglobulin in a mass-volume percentage of at least 18%.
 19. The immunoglobulin preparation according to claim 1, wherein the immunoglobulin preparation comprises immunoglobulin in a mass-volume percentage of at least 20%. 